Magnetic properties of MnZn ferrites prepared by soft chemical routes

Abstract

MnZn ferrites with different composition have been synthesized by soft chemistry routes using oxalate precursors with the partial replacement of water by acetone as the solvent. Toroids were sintered at 1250 °C for 3 h in O2/N2 atmosphere. Sintering conditions significantly changed macroscopic characteristics as density and initial permeability for different composition. Variation of the complex permeability with frequency have been measured over a wide range of frequency, up to 1.8 GHz where dispersion is attributed to spin resonance. No additives for increasing densification were employed. Samples exhibit the highest permeability values for Mn0.8Zn0.2Fe2O4. An anomalous effect is observed when copper is added to MnZn ferrites. The initial permeability (μi) values do not exhibit much variation with temperature, except near Tc where it falls sharply. Curie point and magnetic losses are related with composition.

Structural and Initial Permeability Studies of Li-Zn-Co Ferrites

“…It shows dispersion at low frequency, and becomes nearly constant, maintaining a low value at higher frequencies. Similar observation has been reported by various workers [7][8][9]. At low frequency, change of the magnetization direction occur by the motion of domain walls, so that a domain oriented in the direction of the applied field grows at the expense of its neighbours, which are oriented in different direction.…”

“…3 In ferrites the initial permeability is known to be an interplay of various factors like grain size, density, porosity, saturation magnetization, anisotropy etc [6,7]. The permeability mechanism can be explained in terms of domain wall displacement and rotation of spins in each domain [8][9][10] and is found to be proportional to the square of magnetization, grain size and other factors such as anisotropy etc.…”

Effect of In3+ ions doping on the structural and magnetic properties of Mg0.2Mn0.5Ni0.3InxFe2−xO4 spinel ferrites

“…It decreases with increasing temperature for every composition [51]. RLF has very low values, 10 À 6 -10 À 5 (Table 3), which are about three order of magnitude lower than those reported [52]. In ferrites, two resonance peaks are observed, one due to the domain wall oscillations at lower frequencies and other due to Larmor precession of electron-spins at higher frequencies.…”

Effect of zinc concentration on the structural, electrical and magnetic properties of mixed Mn–Zn and Ni–Zn ferrites synthesized by the citrate precursor technique

“…Higher the density and grain size, greater the grain-to-grain continuity in magnetic flux leading to higher permeability. The high permeability Mn-Zn ferrites are usually reported to show resonance at frequencies less than 1 MHz [26]. The occurring of resonance at higher frequencies for the mixed ferrites shows extended zone of utility for these ferrites.…”